It is well known that the generation or design of a document often includes the use of a computer-based text editing application, such as Microsoft Word, or a graphics software package, such as Microsoft. PowerPoint. After a user generates a document, it can be printed. In the Microsoft Windows printing paradigm, the application works in conjunction with the Windows Operating System's printing subsystem, which generally includes a Graphical Device Interface and printer driver software, to format the document into a print-ready data file that that can be received and interpreted by a printer. These print-ready data files are generally comprised of printer instructions that configure the device for printing the job and direct the device as to how to mark the page. The printer instructions are represented in a specific format, referred to in the printing industry as Page Description Language (PDL). There are many PDLs in existence today, including several that were designed by Hewlett-Packard, such as HP PCL5, HP PCL6 and HPGL/2. In any case, print-ready files can be sent directly to a printer to be printed immediately, or stored for printing at a later time
This process typically applies to all types of printers, including laser printers, ink jet printers, impact printers and thermal printers. In addition, this process also typically applies in general to other hardcopy devices, such as plotters or facsimile machines. Conveniently, herein, the term “printer” covers all such different types of printers, and other hardcopy or document rendering apparatus and devices.
The advent of distributed computer systems made it possible for a single network printer to be used by multiple users. Typically, network printers are attached to computing platforms operating as print servers within distributed systems. Alternatively, some printers, when provided with appropriate interfaces, can be arranged to connect directly to the network of a distributed system.
Network printers, whether connected directly, or via a print server, to a network, can provide a substantial cost advantage, since each user need not have his own printer connected to, or located near to, his own computer system.
The ability to access network printers, and other devices, from a local computer, is readily supported by operating systems such as UNIX, and most of Microsoft's Windows Operating Systems, including Windows ME, Windows 2000, Windows XP, etc. Each of these operating systems are designed to be configured to manage distributed operations such as remote printing or data management.
One problem associated with printing documents on remote network printers is that any person near to the printer can remove or read printed documents containing sensitive information not intended for the person to see. One solution is for users who need to print sensitive documents to arrange for a trusted person to stand by the printer as the document is printing and collect the document as soon as it has printed. This is a very inconvenient solution.
Another solution is to print sensitive documents only on a local printer. The latter case, however, undermines any cost advantages gained in having a centrally located, network printer, especially if many users need to print sensitive documents.
Still another problem associated with remote printing of sensitive documents is that someone can intercept or monitor the transfer of data between the local computer and network printer. For example, anyone with access to a print spooler or print server receiving the document for printing could access the document. When a print job is created, a person on the network can capture the stream of data making up the print job and print it on any device. As a result, content sensitive data can be easily accessed by anyone on a network. The result can be a serious breach of security. Some may contend that this is not a problem since a print format may not be in a text bound language therefore preventing perusal by the naked eye. However, such a binary data stream can be easily converted to text readable output, with the right software tools, resulting in the same security threat discussed previously.